Decided I'm pulling the motor and box out to make way for the new one, been procrastinating long enough with that one. I think this will be the third time the motor has been pulled in 2 years. Got my eye on UAS 6 puk or cushion button, yeah not cheap I'm going to be broke for a bit.
As far as split v Bellmouth dumps go, what is the the best for that type. Best Split pipe?? Best bellmouth?? I'm liking the idea of the tests but it would be a waste if one type was top of the range and the other was the worst ebay spec one avaliable.
the split dumps that i would want to test are the AMS 3in expansion dump, probably the best split dump on the market for 4 bolt turbo's The bellmouth dumps are 3in that i made with minimal restrictions, i dont think they could be improved on in the way of design
Rob look what you started, although it is a good technical subject. Good input from Chad. We have not tested back to back on a zed. We have had plenty of zeds make over 400rwlw with both types. I can comment back to back test same car, being a 2.5 litre Stagea with HKS GTR-S turbo, changed from a nicely made non turbulence 3 inch dump and engine pipe to a bell mouth and made around 9rwkw. I was surprised with this at the time, although after seeing the size of the turbine wheel and seeing the size of the entrance hole in the dump it has to get through with a gap in the middle and with hot spiralling air I suspect, it probably hits an edge. Which is not good. For this reason large turbo's with larger turbine wheels probably better to go bell mouth. I think bell mouth with divider is best of both worlds and this is what Nismo does with cast iron GTR dump pipes. As Black Beast says testing back to back is the only way to know.
Lets 30 of us chip in about $10 each to buy a set of ALLOY TOYS/ AMS 3", 4 Bolt dumps for about $300 & get Niall to test this once & for all! Hopefully before Eric puts my engine & turbo's together, so I can put the best dumps on!
I would like some UAS bellmouth's Simply because they fit. My Ams are boarderline. It doesnt really work.
I remember a thread about 12 months ago where a member got some 2871's and a set of split dump pipes with them which where supplied with NO dividers. The thread was about "shouldnt these have dividers" ??? Anyway he got back onto Z1 who sent back an explaination that the big turbos couldnt run dividers as there was some exhaust gas issue where they actually made less power with the divider in because they couldnt run boost over 20 PSI. So they pull them out where they are supposed to be used with 2871's. Cant find the thread. UAS's explanation about extra power and dyno testing with the bell mouth dumps and the response from Z1 was enough to convince me to go Bellmouth. I have my set of UAS bell mouth dumps for the race car right here ready to go on.
Tekky it was a specialtyz turbo and dump kit, I remember also. I think the explanation was that they were seeing boost creep up due to too much back pressure on wastegate side of the divider.
Yip running a pipe that was to small on the waste gate side of the downpipe so couldn't bleed enough air past the turbine.
i would really like to do back to back tests but untill someone donated a pair of 4 bolt split dumps for testing i cant do it.
no havent had my post replied from greg regarding the splits and big turbos like EXP90 turbos.. Basically the waste gate moves too much air at lower boost settings for the splits to cope with .. bellmouth for huge turbos ... (which should be running external wastegates anyway)
So in saying this, our Z32's can't "practically" run huge turbos on them really, so for our average sized turbos, would you say the Bellmouth design doesn't benefit over the (good quality) split flange design??
If ur keen in a few weeks to test, I'd be happy to send u my Toyz dumps and pay postage there, if u were keen to pay postage back... Unless the forum would like to donate postage $$ for the sake of science! I would love to see the comparison: Stock dumps 2.25" vs Npower/tuneagent split 2.5" vs Toyz 3" vs Big bell mouth (custom) 3" Cmon guys, who's up for a test? If rollin's keen to test the above, let's see whats what! Give generously Funds required (if all items are to be purchased): Stock dumps: Free Npower dumps: $100 tops 2nd hand Toyz dumps: $390 delivered Big bell mouth: Rollin + welder? Need 50 members at $10 a pop! Or 25 members at $20 a pop... Group buy on "curiosity"?
